Fluid shutoff valve

ABSTRACT

A fluid shutoff valve that may be attached to an ordinary lawn hose for controlling the flow of water into a swimming pool. A magnet on a diaphragm holds a movable valve member in the open position and an air chamber at one side of the diaphragm has a fluid connection with a venturi, the chamber also having a fluid connection the open end of which is disposed in the pool at the height whereat it is desired to cut off the supply of water to the pool. The venturi causes air to flow from the second connection and through the chamber when the second fluid connection is above water level in the pool, the flow of air through the chamber being stopped when the water level reaches the open end of the second connection. Air pressure in the chamber is then reduced causing the diaphragm to deactivate the magnet&#39;&#39;s holding of the movable valve member so that said movable valve member is actuated to the closed position by gravity.

United States Patent John S. Neenan 415 Crest Road, Orange, Calif. 92668 805,604

Mar. 10, 1969 Aug. 31, 1971 [72] Inventor [21 1 Appl. No. [22] Filed [45] Patented [54] FLUID SHUTOFF VALVE 3,422,841 1/1969 Farrer ABSTRACT; A fluid shutoff valve that may be attached to an ordinary lawn hose for controlling the flow of water into a swimming pool. A magnet on a diaphragm holds a movable valve member in the open position and an air chamber at one side of the diaphragm has a fluid connection with a venturi, the chamber also having a fluid connection the open end of which is disposed in the pool at the height whereat it is desired to cut off the supply of water to the pool. The venturi causes air to flow from the second connection and through the chamber when the second fluid connection is above water [56] Ram: CM level in the pool, the flow of air through the chamber being UNITED STATES PATENTS stopped when the water level reaches the open end of the 26,631 7/1969 Abbott 251/7'3X second connection. Air pressure in the chamber is then 2,025,665 12/1935 Dickinson 251/228 reduced causing the diaphragm to deactivate the magnets 2,587,358 2/ 1952 McRae 137/463 holding of the movable valve member so that said movable 3,254,660 6/1966 Ray 25 1/228 X valve member is actuated to the closed position by gravity.

24 l o 70 E 94 E 40 .94 3'2 5 38 /2 .36 H Q 4. A 34 r /3 30 32 //2 \\\\\\\X\\y(\\\\ /4 2p 80 58 FLUID SHUTOFF VALVE BACKGROUND OF THE INVENTION 1. Field of the Invention A portable shutoff valve for attachment to a water supply conduit for swimming pools and the like for shutting off the supply of water to the pool when a predetermined top level is reached in the pool.

Description of the Prior Art In the past various types of valve mechanism have been devised and used for automatically controlling the water level in swimming pools. Such valve mechanisms are generally attached to the discharge end of a fixed water supply pipe or conduit and extend into the pool so there is always a possibility of a swimmer striking the valve and being injured.

Another difficulty presented by such previous valve mechanisms is the difficulty of installation and maintenance Also such valves attempt to automatically open when the water level drops below a predetermined level and to close when the water level reaches apredetermined high level. Such valve mechanisms are complicated and expensive and servicing and/or repair thereof is likewise expensive.

' SUMMARY OF THE INVENTION The present invention comprises a housing defining a water chamber having a diaphragm above the top wall of said chamber. The diaphragm has a magnet attached thereto and said diaphragm is peripherally secured by a cap which defines an air chamber. Water enters the housing water chamber at one side and is adapted to leave the housing at the opposite side by way of an outlet port, there being a venturi at the downstream end of the outlet port and a valve seat at the upstream end of said port.

.A movable valve member is adapted to seat on said valve seat but is held in an open position by the magnet attached to the diaphragm while the latter is in a lower position. The air chamber is connected to the venturi and also has a conduit connection with a level-sensing conduit which is adapted to depend within the swimming pool with the lower, open end at the desired upper level for the water in the pool.

Normally, when the level of water in the pool is below the lower end of the sensing conduit air is drawn through said sensing conduit, air chamber and into the venturi so that air pressure in the air chamber is substantially atmospheric pressure. When the pool is being filled with water and the water level reaches the lower end of the sensing conduit, air flow through said sensing conduit is stopped. Air continues to be drawn from the air chamber by the flow of water through the venturi thus lowering the air pressure in the air chamber which results in the diaphragm being raised which consequently raises the magnet. The movable valve member then drops by gravity to the valve-closed position thereby shutting off the flow of water into the pool.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide a shutoff valve that is portable and that may be quickly connected and disconnected from a lawn hose or the like.

Another object of the invention is to provide a valve of this character that may be placed on the edge or coping of a swimming pool for filling sameand that will automatically shut off the water when the water level reaches a predetermined high level.

Still another object of the invention is to provide a device of this character that may be simply picked up and removed from the pool-filling position and be placed out of the way as in storage until needed again.

A further object of the invention is to provide a device of this character that is very inexpensive to manufacture, simple in construction and reliable in operation.

The characteristics and advantages of the invention are further sufficiently referred to in connection with the following detailed description of the accompanying drawings which represent certain embodiments. After considering these examples skilled persons will understand that many variations may be made without departing from the principles disclosed and l contemplate the employment of any structures, arrangements or modes of operation that are properly within the scope of the appended claims.

Referring to the drawings, which are for illustrative purposes only:

FIG. 1 is a perspective view of a valve embodying the present invention attached to a hose and disposed for filling a swimming pool to a predetermined high level;

FIG. 2 is a sectional elevational view taken on line 2-2 of FIG. 1 showing the movable valve member in the open position;

FIG. 3 is a similar view of the valve mechanism per se in the closed position;

FIG. 4 is an elevational sectional view taken n line 44 of FIG. 3;

FIG. 5 is a sectional view of an alternative arrangement;

FIG. 6 is a side elevational view, with portions broken away, of an alternative arrangement using an electromagnet holding the movable valve member in the open position, the switch for the electromagnet being closed;

FIG. 7 is a fragmentary sectional view showing the switch for the electromagnet in the open position and the movable valve member in the closed position; and

FIG. 8 is a sectional view taken on line 8-8 of FIG. 6.

Similar reference numerals refer to similar parts throughout the application.

Referring more particularly to FIGS. 1 to 4, there is shown a shutoff valve, indicated generally at 10, which embodies the invention. There is a housing, indicated generally at 11, having front, rear, side and bottom walls l4, 16, 18 and 20 respectively. An inwardly extending flange 22 defines an opening 24 at the top of the housing.

Rear wall 16 has an outwardly projecting tubular nipple 26 having an internally threaded nut 28 rotatably' attached thereto in the usual well-known manner for attachment to the externally threaded female part 30 of a conduit or hose 32. These parts are well known in construction and operation.

Front wall 14 is relatively thick and has an outlet passage 34 extending forwardly from a valve seat 36 about an outlet port 38 which is the entrance to the passage 34. Passage 34 flares from its downstream end, as at 40, to define a venturi, the large downstream end of which communicates with the interior passage 42 of an outlet conduit 44 which has a downturned forward or free end or spout 46. The housing 1 1 may be of any suitable material although a nonmagnetic material may be used. Aluminum or stiff rigid plastic are examples of suitable material.

Opening 24 in the top of the housing 11 is closed by a stiff or rigid partition, indicated generally at 50, having a depending, upwardly opening axial or central well 52, and having a peripheral edge portion 54 disposed on an upturned flange 56.

There is a shallow cup-shaped cover, indicated generally at 57, having a top wall 58 and a downturned flange 60, the cover being secured to the housing by screws, not shown, or any other suitable means. Flange 60 has a recess 64 in the free edge, said recess being open at the inner side and receiving a peripheral edge portion of a flexible diaphragm 66, the peripheral edge portions of the partition and diaphragm being clamped between the flange 56 of the housing and the flange 60 of the cap. There is an atmospheric vent 67 for venting to atmosphere a chamber 69 below diaphragm 66.

Partition 50 is of nonmagnetic material. It is shown as being of plastic although it may be of aluminum or other nonmagnetic material. Also, the partition, or at least the bottom wall 70 of the well 52 should be relatively thin, that is thin enough so that magnetic pull by a magnet 72 secured to the diaphragm 66 may be effective therethrough. Magnet 72 may be of any suitable character although as shown it is a ceramic magnet. The diameter of the magnet 72 is somewhat smaller than the diameter of the well 52 so that the magnet may freely move out of and into said well with upward and downward movements of the diaphragm 66.

Diaphragm 66 and cap 57 define an air chamber 76 the pressure in which controls the position of the diaphragm 66. Top wall 58 of the cap 57 has an upstanding nipple 78 with an air passage therethrough and on which one end of a conduit 80 is disposed. Conduit 80 has its other end attached to a nipple 82 of wall 14, the nipple 82 having a passage therethrough which is an extension of a passage 84 in wall 14, the latter passage communicating with the interior of the venturi 40. With this arrangement air is drawn from the chamber 76 by the drop in water pressure flowing through said venturi.

Cap 57 also has a nipple 86 with a passage through communicating with said air chamber 66. A conduit 88 has one end attached to the nipple 86. While conduit 88 has may be of any suitable character it has been found that a flexible plastic conduit is highly satisfactory, there being weight 90 on the lower free end of said conduit. The weight holds the lower end of the conduit 88 downwardly.

Within the water chamber 12 is disposed a flapper valve, indicated generally at 94, which comprises a body 96 with a cutout part having ears 98 at the ends thereof and best shown in FIG. 4. These ears have aligned horizontal openings therethrough for reception of a pivot pin 100 end portions of which are disposed in oppositely arranged lugs 102 at the upper downstream end of chamber 12. The valve 94 is adapted to swing or pivot on said pivot pin 100.

it is desirable to have the valve 94 relatively light in weight and of suitable material. For example the valve body may be of stiff or rigid plastic or it may be of aluminum. Valve 94 is adapted to swing from a horizontal position, FIG. 2 to a vertical position, FIGS. 3 and 4.

Secured to one side of the valve body 96 by a suitable adhesive or by a screw, not shown, is a disc or part 104 of material that is attracted by magnetic force. The part 104 is at the top side of the body 96 when the latter isin the horizontal position and abuts against the underside of the bottom wall 70 of the well 52 so that it is attracted toward the magnet 72 thereby holding the valve 94 in the horizontal open position when the magnet is in well 52. Alternatively the, valve may be a lightweight piece of steel or the like.

When it is desired to fill or bring the water in the swimming pool, indicated generally at 110, to a top level, the valve mechanism is disposed on the coping 112 of pool 110 with the conduit 88 depending into the pool, as shown in FIG. 1. The water level 114 in the pool below the desired level, the lower free end of the conduit 88 is positioned above said level and at the desired or full level. The lower free end of conduit 88 is unimpeded and when water is flowing through the mechanism air in chamber 76 is kept at a normal pressure, which is substantially atmospheric pressure, by the flow of air into chamber 76 by way of conduit 88 as air is drawn from chamber 76 by the action of venturi 40.

The weight of the magnet 72 normally maintains said magnet in its well 52 so that the valve 94 is held in the open position. A baffle 116 which is part of the partition 50 depends into the chamber 12 and upstream of the valve 94 to prevent the water flowing through chamber 12 from dislodging the valve 94 from its open position.

When the water level rises sufficiently to reach and close the lower open end of the conduit 88 the flow of air into the air chamber 76 is cut off. Due to venturi suction the air pressure in chamber 76 is lowered and the diaphragm 66 is pulled upwardly thereby pulling the magnet 72 upwardly, thus weakening the magnetic pull on the part 104 of the flapper valve which thereupon swings downwardly by force of gravity and into the closed position. Valve 94 has a sealing disc or washer 120 secured to the side opposite the part 104.

The disc 120 seats on the valve seat when the valve 94 is in the closed position and said disc is of a suitable resilient material such as rubber, natural or synthetic. The term plastic, as used herein, may be considered as included in the term synthetic rubber.

Thus the water to the pool is cut off at the desired pool level. Thereafter the water faucet or the like to which the hose 32 is attached, is closed. Resetting of the valve 94 is easily effected by flipping the mechanism upwardly so that the magnet, which returns to its well 52 when the flow of water through the venturi stops, will again hold the valve 94 in its open position. Another means for resetting the valve 94 in its open position is to hold the mechanism with the spout part 44 and 46 upwardly so that the valve 94 then hangs adjacent to or against the bottom wall 70 of the well 52.

Referring to FIG. 5 there is shown an alternative arrangement of the shutoff mechanism. The housing in this embodiment has an inlet chamber and an outlet chamber 132 separated by a horizontal partition 134 having an outlet opening or port therein defined by a valve seat 136 which tapers downwardly.

Inlet chamber 130 has a horizontal top wall 138 from which depends a cylindrical flange 140 the lower end of which is spaced somewhat upwardly of the partition. Flange 140 defines a cylindrical valve chamber closed at the top and in which a movable valve member, indicated generally at 142, is slidable longitudinally upwardly and downwardly.

Valve member 142 is of relatively lightweight material such as plastic, aluminum or the like. At the upper end said valve member has attached thereto by any suitable and effective means a disc 144 of material that is magnetically attractable. The means for securing the disc 144 to the valve member may be a suitable adhesive or a screw, not shown. At its lower end said valve member has a frustoconical head 148 adapted to seat on the valve seat 136 when the valve member 142 is in its lower or closed position. v

The housing has an upwardly extending flange 150 between the upper end of which and the lower end of a depending flange 152 of a cap, indicated generally at 154, is clamped a peripheral edge portion of a flexible diaphragm 156. Cap 154 is in the shape of a shallow cup and has a top wall 158, said cap being secured to the housing by any suitable means such as screws, not shown.

Diaphragm 156 has a magnet 160 attached thereto by any suitable means such as an epoxy adhesive, for example. Any other suitable attaching means may be also be used. The magnet is centrally located on the diaphragm and normally rests on the partition 138 in alignment with the valve 142.

Inlet chamber 130 is supplied with water through a tubular nipple having a nut 28 rotatably mounted thereon, said nut being adapted to be connected to a hose or the like as with the arrangement of FIGS. 1 to 4.

Outlet chamber 132 has an outlet port 162 and a venturi 164 is positioned downstream of said outlet port. An air chamber 166 above diaphragm 156 is defined by said diaphragm and the cap 154. A nipple 168 extends from the top wall 158 of the cover and has an air passage therethrough. One end of a conduit 170 is attached to said nipple 168. The other end of said conduit 170 is attached to a nipple 172 extending outwardly from the wall of the outlet conduit 44 in which the venturi is disposed. Thus the air chamber 166 is connected to the throat 176 of the venturi 164. There is a chamber 178 below the diaphragm 156 which is provided with an atmosphere vent 180. A part 46 may be attached to the outer or discharge end of conduit 44.

Air chamber 166 is also provided with a nipple to which one end of a conduit 88 is attached, said conduit being described above.

The magnet 160 normally holds the valve 142 in the upper or open position as long as the air pressure in chamber 166 is substantially atmospheric due to the air supplied thereto through the conduit 88. When air pressure is reduced by the closing of the open end of conduit 88 by water rising in the pool, the diaphragm 156 pulls the magnet upwardly whereupon valve 142 drops to the closed position under the force of gravity, the head 148 of said valve seating on the valve seat 136.

The magnet 160 may be strong enough to raise the valve member 142 when said magnet is in the normal position resting on the partition 138.

Should the magnet not be strong enough to raise the valve 142 as described above the mechanism may be given an upward flip to bring the upper end of said valve into contact with the partition.

The housing and other various parts of the mechanism are of plastic, aluminum or other suitable nonmagnetic material.

It is to be understood that the cylindrical flange 140 not only serves as a guide for the valve member 142 but also serves as a shield to prevent water flowing through the inlet chamber 130 from causing the valve member to close the outlet port of said inlet chamber.

In the arrangement shown in FIGS. 6, 7 and 8, there is shown the chamber 12 supplied-with water by the hose or conduit 32. Discharge of water from the chamber 12 into the outlet conduit 44 is through a venturi 200. Movable valve member 94 is pivoted on pin 100 as the movable valve member in the arrangement of FlGS. 1 to 4.

A horizontal partition or wall 202 is disposed between chamber 12 and a chamber 204, said wall 202 being relatively thin but of sufficient strength to withstand any water pressure that there might be in chamber 12.

Chamber 204 is enclosed by sidewalls 206 and 208, rear wall 210, front wall 212 and a cover 214 that is press fitted into an internal recess in walls 206, 208, 210, and 212. An atmospheric vent 216 is provided-for chamber 204.

Within chamber 204 is an electromagnet, indicated generally at 220, disposed on the partition or wall 202 and is secured by any suitable means such as a suitable adhesive or a screw, not shown. Electromagnet 220 has a core terminating at the lower end in an enlargeddisc 222, there being the usual coil of wire about the core, said coil being enclosed by a cover 224.

Chamber 12 has a recess portion 228 for reception of a battery 230. When the battery is in place in the recess 228, the pole or terminal 232 of one end of the battery 230 engages a contact member 234 which in turn is connected to a terminal 235 of one end of the coil of the electromagnet 220 by a wire 236. The other end or terminal 238 of the battery contacts contact member 240 which is connected by a wire 242 with a fixed contact member 244 of a switch, indicated generally at 246. Switch 246 has another fixed contact member 248 adjacent to but spaced from the fixed contact member 244, said fixed contact member 248 being connected to a terminal 249 at the other end of the coil of the electromagnet by a wire 250.

Front wall 212 of chamber 204 is of substantial thickness and has a cylindrical wall 252 defining a chamber in which is received a cup-shaped cap 254 disposed in said chamber and in turn defining a chamber 258. The inner end of cap 254 clamps a peripheral portion of a diaphragm 260 against the adjacent end portion of wall 212. Wall 212 has a bore 264 communicating with chamber 204 and in said bore there is slidingly disposed a plunger 266having an end portion 268 of reduced diameter said end portion 268 being of metal and adapted to engage the contact members 244 and 248 and complete the circuit to the coil of the electromagnet.

Plunger 266 is secured to diaphragm 260 by any suitable means such as an adhesive, for example. and a spring 270 in chamber 258 reacts between outer end wall 272 of cap 254 and the diaphragm 260, there being spring retainers provided on the end wall and diaphragm respectively for the ends of spring 270. The cap 254 is retained in position in the chamber defined by the wall 252 by a screw 274. End wall 272 of the cap 254 has a nipple 276 to which one end of the conduit 88 is attached, said nipple having a passage therethrough for fluid communication between said chamber 258 and conduit 88. At the plunger side of the diaphragm 260 the wall 212 is provided with a recess 278 which is vented to atmosphere by a vent passage 280 in wall 212. Chamber 258 is connected with the venturi 200 by a passage 282 in the wall of the venturi and a port or orifice 284 in the wall of the cap 254.

Wall 212 has a radial bore 29 therein, an outer end portion 292 of which is tapped for reception of a plug 294 screwed into the tapped bore portion 292. Plug 292 has an axial bore, therethrough, smaller in diameter than the bore 290, which registers with a bore of comparable size in the wall 212 and which extends from the inner end of bore 290 into the bore 264 in which the plunger 266 is disposed. A pin 298 is slidably disposed in the bore of the plug 294 and the bore from the bottom or inner end of the bore 290 into the bore 264. Pin 298 has a washer 300 thereon. The washer may be secured by a pin or the like, not shown. A spring 302 is disposed in the bore 290 and on the pin, said spring reacting between the inner end of plug 292 and the washer to urge the pin inwardly and has a head 304 at the outer free end to facilitate taking hold of the pin.

Normally the plunger 266 is at its inner position, as shown in FIGS. 6 and 8, urged to said position by the spring 270. When in this position the metal end 268 contacts both of the fixed contacts 244 and 248 so that the switch 246 is closed and current is supplied to the coil of the electromagnet to energize same. By holding the conduit 44 upwardly the movable valve member 94 swings downwardly into contact with the wall 202 at which position the energized electromagnet is effective to hold the valve which is then in the open position so that water may flow through the chamber 12, through the venturi, the conduit 44 and out the end or spout 46.

The device is positioned on the coping 112 in the manner described in connection with the arrangements of FIGS. 1 through 5 and it functions in the same manner. That is, when the water level in the pool is below the depending open end of the conduit 88 the pressure in chamber 258 is substantially atmospheric and the spring 270 keeps the plunger 266 at its inward position whereat the end 268 contacts fixed contact members 244 and 248 of the switch 246.

When the water level reaches the open end of said conduit 88 air cannot flow into conduit 88 and chamber 258 whereupon suction at the venturi throat causes a reduction in pressure in said chamber 258 which pulls the diaphragm 260 toward the left, as viewed in FIGS. 6, 7 and 8, which in turn retracts the plunger 266 and end 268 so that said end 268 moves out of contact with the fixed contact members 244 and 248, thereby opening switch 246 and deenergizing the electromagnet. This results in the valve member 94 swinging downwardly to rest on the valve seat 308 at the entrance to the venturi 200 and cutting off the flow of water through the venturi, into the conduit 44,- and out through the nozzle 46.

When the plunger 266 is thus retracted its inner end clears the inner end of the pin 298 and spring 302 moves the pin inwardly so an inner end portion is in the path of the plunger 266 and the shoulder 310 at the junction of the reduced diameter portion 268 of the plunger and the inner end of said plunger engages the inner end portion of the pin. Thus the plunger is releasably held in a retracted position whereat the switch 246 is open, the electromagnet is deenergized so it will not attract valve 94. Further, since no electric current is supplied to the electromagnet there is no drain on the battery. it is only when the device is open that electric current is required from the battery.

l claim:

1. A shutoff valve mechanism for a pool or the like, comprising:

A. a hollow housing having a chamber with a liquid inlet and a liquid outlet port;

B. a nonmagnetic partition defining part of said housing;

C. a venturi downstream of said outlet port;

D. a movable valve member at one side of said partition, said movable valve member being movable between an open position and a closed position shutting off outflow of liquid from said chamber, said valve having at least a part of magnetically attractable material;

E. means, including a movable pressure-sensitive element defining a pressure chamber, said pressure-sensitive element being exposed to the pressure in said pressure chamber; F. a magnet at the other side of said partition, said magnet being adjacent to and aligned with at least the magnetically attractable part of the valve member for direct magnetic attraction of said attractable part of said valve member when the latter is in the open position;

G. a fluid connection between said pressure chamber and said venturi;

H. a sensing conduit connected to said pressure chamber, said magnet being adapted to retain the movable valve member in the open position when the pressure in said pressure chamber is normal but when said sensing conduit is closed the pressure in said pressure chamber is reduced and the pressure-sensitive element is moved to effect reduction in the magnetic force acting on the v movable valve member and allow said valve member to move to its closed position.

2. The invention defined by claim 1, wherein the magnet is a permanent magnet and is attached to and movable with the diaphragm, whereby said magnet is moved away from said valve member when the pressure is reduced in said pressure chamber.

3. The invention defined by claim 1, including means for protecting the movable valve member from liquid flow in the housing.

4. The invention defined by claim 3, wherein the movable valve member is a flapper valve movable between a horizontal position and a vertical position, said valve being in the open position when horizontal and in the closed position when vertical.

5. The invention defined by claim 4, wherein the means for protecting the movable valve member from fluid flow in the housing comprises a baffle adjacent to but spaced from the free end of the movable valve member.

6. The invention defined by claim 3, wherein the movable valve member is a reciprocal valve member and the means for protecting the movable valve member from liquid flow in the housing comprises a cylindrical flange open at the lower end and in which said movable valve member is adapted to reciprocate.

7. The invention defined by claim 6, wherein the housing has a horizontal partition therein separating said housing into an inlet chamber and an outlet chamber, said partition having a port therein for the flow of liquid from said inlet chamber into the outlet chamber, and said movable valve member has a valve head at the lower end for seating in said port to cut off the flow of liquid from said inlet chamber into said outlet chamber.

8. The invention defined by claim 1, wherein the sensing conduit is flexible and there is a weight at the lower end thereof.

9. The invention defined by claim 1, wherein the movable pressure-sensitive element comprises a flexible diaphragm.

10. The invention defined by claim 1, wherein the magnet is an electromagnet secured in position adjacent to said partition, and there is an electric switch connected operably to said electromagnet and adapted to be connected to a source of electric power, said switch being operably connected to said pressure-sensitive element and controlled thereby.

11. The invention defined by claim 10, wherein said switch is normally closed and includes a movable contact connected to said pressure-sensitive element and controlled thereby, said movable contact being moved to a switch-open position when the pressure-sensitive element responds to a reduction in pressure in the pressure chamber upon closing of the sensing conduit.

12. The invention defined by claim 11, including a latch for retaining the movable contact in the open position, said latch being releasable to permit the movable contact to move to the switch-closed position.

13. The invention defined by claim 12, wherein said latch automatically latches the movable contact in the open position. 

1. A shutoff valve mechanism for a pool or the like, comprising: A. a hollow housing having a chamber with a liquid inlet and a liquid outlet port; B. a nonmagnetic partition defining part of said housing; C. a venturi downstream of said outlet port; D. a movable valve member at one side of said partition, said movable valve member being movable between an open position and a closed position shutting off outflow of liquid from said chamber, said valve having at least a part of magnetically attractable material; E. means, including a movable pressure-sensitive element defining a pressure chamber, said pressure-sensitive element being exposed to the pressure in said pressure chamber; F. a magnet at the other side of said partition, said magnet being adjacent to and aligned with at least the magnetically attractable part of the valve member for direct magnetic attraction of said attractable part of said valve member when the latter is in the open position; G. a fluid connection between said pressure chamber and said venturi; H. a sensing conduit connected to said pressure chamber, said magnet being adapted to retain the movable valve member in the open position when the pressure in said pressure chamber is normal but when said sensing conduit is closed the pressure in said pressure chamber is reduced and the pressure-sensitive element is moved to effect reduction in the magnetic force acting on the movable valve member and allow said valve member to move to its closed position.
 2. The invention defined by claim 1, wherein the magnet is a permanent magnet and is attached to and movable with the diaphragm, whereby said magnet is moved away from said valve member when the pressure is reduced in said pressure chamber.
 3. The invention defined by claim 1, including means for protecting the movable valve member from liquid flow in the housing.
 4. The invention defined by claim 3, wherein the movable valve member is a flapper valve movable between a horizontal position and a vertical position, said valve being in the open position when horizontal and in the closed position when vertical.
 5. The invention defined by claim 4, wherein the means for protecting the movable valve member from fluid flow in the housing comprises a baffle adjacent to but spaced from the free end of the movable valve member.
 6. The invention defined by claim 3, wherein the movable valve member is a reciprocal valve member and the means for protecting the movable valve member from liquid flow in the housing comprises a cylindrical flange open at the lower end and in which said movable valve member is adapted to reciprocate.
 7. The invention defined by claim 6, wherein the housing has a horizontal partition therein separating said housing into an inlet chamber and an outleT chamber, said partition having a port therein for the flow of liquid from said inlet chamber into the outlet chamber, and said movable valve member has a valve head at the lower end for seating in said port to cut off the flow of liquid from said inlet chamber into said outlet chamber.
 8. The invention defined by claim 1, wherein the sensing conduit is flexible and there is a weight at the lower end thereof.
 9. The invention defined by claim 1, wherein the movable pressure-sensitive element comprises a flexible diaphragm.
 10. The invention defined by claim 1, wherein the magnet is an electromagnet secured in position adjacent to said partition, and there is an electric switch connected operably to said electromagnet and adapted to be connected to a source of electric power, said switch being operably connected to said pressure-sensitive element and controlled thereby.
 11. The invention defined by claim 10, wherein said switch is normally closed and includes a movable contact connected to said pressure-sensitive element and controlled thereby, said movable contact being moved to a switch-open position when the pressure-sensitive element responds to a reduction in pressure in the pressure chamber upon closing of the sensing conduit.
 12. The invention defined by claim 11, including a latch for retaining the movable contact in the open position, said latch being releasable to permit the movable contact to move to the switch-closed position.
 13. The invention defined by claim 12, wherein said latch automatically latches the movable contact in the open position. 